X-ray diffraction (XRD) is the primary, non-destructive tool for identifying and quantifying the mineralogy of crystalline compounds in rocks, soils and particulates. Every mineral or compound has a characteristic X-ray diffraction pattern whose 'fingerprint' can be matched against a database of over 250 000 recorded phases. Modern computer-controlled diffraction systems can interpret the diffraction traces produced by individual constituents and highly complex mixtures.
XRD is an essential technique for identifying and characterising the nature of clay minerals, providing information which cannot be determined by any other method.
How does X-ray diffraction work?
when monochromatic X-rays are projected onto a crystalline material at an angle (θ), diffraction occurs when the distance traveled
by the rays reflected from successive planes differs by an integer(n) of wavelengths (λ)
By varying the angle θ, the Bragg's Law conditions [nθ =
2d sinθ] are satisfied by different d-spacings
Plotting the angular positions and intensities of the resultant
diffracted peaks produces a characteristic pattern
where different phases are present, the diffraction trace represents the sum of the individual patterns
state-of-the-art PANalytical X’Pert Pro diffractometer which can
be flexibly configured with flat spinning or capillary stages, 45-position sample changer, temperature/humidity chamber for either routine or
backup Philips PW1700 series diffractometer
latest versions of the internationally-recognised ICDD and ICSD
PANalytical HighScore Plus analytical software including Rietveld refinement for quantification.
The XRD laboratories at Keyworth play a key role in projects that
span the BGS science programme, for example:
characterisation of lithologies intended for radioactive waste
disposal and carbon dioxide capture/storage
researching changes in soil clay mineralogy with different land
determining the contribution of clay minerals to the engineering
behaviour of rocks and soils
distinguishing natural and anthropogenic sources of toxic elements in brown field sites
providing forensic evidence
providing indicators of geological history, basin maturity and
low grade metamorphism
Staff and facilities are also in constant demand for direct consultancy analysis and interpretation by external clients including: oil, mineral and mining companies; engineering and utility companies; consultancies; university departments and local authorities.